Biocompatible Self-Lubricating Polymer Compositions and Their Use in Medical and Surgical Devices

ABSTRACT

The invention comprises self-lubricating polymer compositions that are especially useful in medical devices and valves and gaskets of medical devices. In a preferred embodiment, the polymer compositions comprise a thermosetting or thermoplastic silicone elastomer in combination with a lubricity enhancing polyfluoropolyether fluid or hydrocarbon-based synthetic oil. In other preferred embodiments, the polymer compositions contain only biocompatible components. The improved anti-friction properties of the self-lubricating polymers can be demonstrated over a course of insertion and withdrawal cycles, where conventional polymers have changing and mostly increasing force required for each insertion and withdrawal, while the polymer compositions of the invention remain stable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/594,165, filed 12 May 2017, now pending, which is a continuation ofU.S. application Ser. No. 11/482,814, filed 10 Jul. 2006, now abandoned,which claims the benefit of U.S. provisional application No. 60/795,593,filed 28 Apr. 2006, now expired. This application is also related tointernational application no. PCT/US07/67407. The foregoing are herebyincorporated by reference as though fully set forth herein.

FIELD OF THE INVENTION

The invention relates to polymer compositions with enhancedanti-friction properties for use in medical applications and medicaldevices. The polymer compositions have reduced friction characteristicsand can be implemented in tubing, gaskets, valves, and in a variety ofinsertion devices and other devices used in procedures to introduceobjects into the body, for example.

BACKGROUND

A growing number of surgical or medical procedures employ devices andkits that rely on inserting a device or tube through a sealed valve orapparatus. For example, catheters and guides are typically insertedthrough a sterile valve to introduce fluids, intraluminal devices andmany other instruments into the body or into the lumen of a bloodvessel. In fact, various surgical kits now include valves and devices toassist in the simultaneous, sterile insertion of multiple elements intovessels or elsewhere in the body. To operate properly, the valves mustbe capable of accepting different sized elements, be sufficientlypliable and/or elastic to maintain a seal during manipulation, and allowthe user to effectively introduce and remove devices under sufficientcontrol to avoid damage to vessels or other body tissue. However,pliable or flexible polymers tend to cause a degree of friction when anelement is inserted or withdrawn into or through them. During medical orsurgical procedures, this friction is undesirable and may lead to a lackof control and require forceful insertion or withdrawal. Some kits andprocedures even require multiple guidewire and catheter exchange steps,for example, which exacerbates the insertion and withdrawal problems.The sealed or sealable valves used must also prevent the introduction ofair into a blood vessel and/or contamination of body tissue duringinsertion and withdrawal. Because of these and other requirements, thesafe insertion and withdrawal, as well as the related forces used toinsert and withdraw, has become a problem with many devices and kitsused today. To attempt to alleviate this problem, silicone oil iscustomarily used to externally lubricate the valves and devices. Duringa medical procedure, this lubricant can be wiped away or lose itseffectiveness after even a single insertion and withdrawal action.

A high performance hemostasis valve has recently been described that canbe sealed effectively to prevent leaks and contamination and which iscapable of accepting various catheters having a variety of diameters(see, for example, U.S. Pat. No. 6,632,200). As described below, theinventors' improvements on this and many other devices, which in partaddresses the friction problem during insertion and withdrawal notedabove, includes a self-lubricating polymer composition that effectivelyallows elements to slide in and out of valves, other devices, tubes, orthrough tissue in a more controlled and easier manner. Accordingly, theuse of the self-lubricating polymer compositions of the inventionimproves the performance and use of a variety of medical and surgicaldevices and kits. In addition, the polymer compositions can be used toimprove basic catheter and tubing applications, or wherever one materialslides over or across another material in a sealed or sealable device,valve, or gasket.

BRIEF SUMMARY

In one aspect, the invention addresses the use of a self-lubricatingpolymer composition to make at least a part of or element to a medicalor surgical device, or a kit comprising such medical or surgicaldevices. In some applications, it is desirable for these polymers to beflexible enough to form a sufficient seal around the surface of anyelement inserted into it and/or in contact with it during the course ofusing the device. For example, the self-lubricating polymer can be usedas a gasket at or around the insertion site of a guide or catheter.Similarly, the guide or catheter itself can be made of, or at leastpartially made of, the self-lubricating polymer.

In a general aspect, the invention addresses the use of a polymermaterial at a semidynamic seal, such as where one part moves along,slides over, or contacts another part or element in the practice or useof a medical or surgical device, and/or at a dynamic seal, where two ormore parts similarly contact or move against each other. Variousgaskets, valves, covers and other sealing structures can be used inmedical and surgical devices to produce a semidynamic or dynamic seal.Thus, any of the existing and/or future sealing structures can beimproved through the use of the polymer compositions of the invention.

In another general aspect, the invention provides self-lubricating orenhanced lubricity polymer compositions for use in medical and surgicaldevices and related applications. The term lubricity is used in theconventional sense of a lubricating characteristic that effectivelyreduces friction between rubbing or contact surfaces. Lubricity can bemost important in conditions of boundary lubrication and/or forcontinuously maintaining a low surface-energy and/or to effectivelyrepel body fluids and the resulting drag forces on contact surfaces. Byincreasing the lubricity of the polymer material used, the degree ofdeformation can be limited for a particular structure to form ormaintain a leak-proof seal, while the force needed to slide over orthrough the structure is reduced. A preferred example of aself-lubricating polymer composition comprises a biocompatibleelastomer, and especially preferred is a biocompatible siliconeelastomer. Other biocompatible blends of elastomers and/or thermoplasticpolymers can also be used, as known in the art. The self-lubricatingcompositions also comprise one or more lubricants, such as syntheticoils and/or solid lubricants. Preferred synthetic oil lubricants arepolyfluoropolyether (PFPE) synthetic oils, and hydrocarbon-basedsynthetic oils, namely co-oligomers of ethylene and olefins. Preferredsolid lubricants include low molecular weight polytetrafluoroethylenepowders, titanium dioxide micropowders, molybdenum disulfidemicropowders, graphite micropowders or flakes, and baron nitridemicropowders and the like. Any combination of these lubricants andothers available and/or used in the art for biocompatible materials canbe selected, and preferred combinations are given in the Examples.

As noted above, the self-lubricating polymer compositions can be used toproduce one or more parts or elements in a medical or surgical device.In one preferred example, the part or element can comprise all or partof an insertion device or a receiving area for an inserted device orother elongated medical device. Typically, a receiving area employs agasket or seal, which can readily and/or repeatedly permit passage ofone or more devices, optionally of varying diameters. The gasket or sealor other receiving area is comprised of the polymer composition of theinvention and thus has improved lubricity characteristics, for examplewith respect to a reduction in insertion and withdrawal forces comparedto other materials and/or a reduction in the fluctuation of frictionalforces during repeated or regular use. The receiving area can also be orcomprise a centering orifice for inserting a device, which functions toposition or center the inserted device into a particular region.Furthermore, multilayered structures may also be used, wherein at leastone layer comprises a self-lubricating composition of the invention,preferably a layer in contact with another component or against whichfrictional forces are generated during use. In a preferred example, theouter layer of an inserting device and/or the inner layer of a receivingarea, such as a gasket, sheath or seal, comprises a biocompatibleself-lubricating composition of the invention. In addition, variouslengths of the inserting device or receiving area can comprise aself-lubricating polymer composition of the invention, anywhere from theentire insertion length, to less than 10% of the insertion length, toonly the tip or inserting end of the insertion device, and evenintermittent or non-contiguous sections covering a desired percentage ofthe insertion length can be used. Thus, a multilayered tube or sheathcan be made and used, and one of skill in the art is familiar withmolding and co-extrusion processes, for example, for producing theseparts of medical devices.

Accordingly, it is one object of the invention to provide a medical orsurgical device that comprises a receiving area and/or insertion devicemade at least in part of a self-lubricating polymer composition. Theparts, elements, biomedical, medical or surgical devices that containthe receiving areas or comprise insertion devices can thus exhibitimproved anti-friction performance in the ease with which insertion andwithdrawal of elongated elements or parts occurs and in the maintenanceof adequate sealing characteristics to avoid or substantially avoidleakage of fluids, blood, or the flow of air during use. It is anadditional object to provide a biocompatible polymer for use inbiomedical applications, including human, veterinary, and biomedicalresearch fields, wherein a self-lubricating polymer of the inventionprovides an improved lubricity surface for inserting into or withdrawingfrom or out of a variety of devices or body tissues.

Other objects, features, details, utilities, and advantages of thepresent invention will be apparent from the following more particularwritten description of various embodiments and examples of theinvention, as further illustrated in the accompanying drawings anddefined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional view of preferred cardiac catheterdevice comprising hub 10 containing a hemostasis valve as exemplaryreceiving area, a stopcock assembly 12, a guidewire 20, and a cathetersheath or shaft 30 extending into the lumen of a vessel. The valvereceiving area comprises a gasket or seal made of a self-lubricatingpolymer of the invention primarily comprising a silicone elastomer and asynthetic oil. The forces required to introduce, manipulate, control,and/or withdraw the catheter device are substantially less than thosewhen a conventional elastomer without modification is used for thegasket or seal.

FIG. 2 depicts a close-up, cross-sectional view of an inserting device200 inserted into a hemostasis valve, where various parts or elements ofthe valve can be made of the self-lubricating polymer of the invention.For example, sheath 100 (on its inner and/or outer surface) and gasketarea 200 can both be composed of the self-lubricating polymercompositions of the invention to improve performance, such asanti-friction and sealing performance.

FIG. 3 is a radial, cross-sectional view of a catheter sheath or shaft120 passing through the gasket 43 of a valve, for example, similarly,any tubing used in or inserted into a body tissue can be made of aself-lubricating polymer composition of the invention.

FIG. 4 shows exemplary results of an insertion and withdrawal cycleperformed on a hemostasis valve produced from the formulation inExample 1. Each spike represents the forces measured in one of fourteeninsertion/withdrawal cycles, and the ten separate lines represent one often different catheters inserted into the same hemostasis valve. Evenafter the unusually large number of insertions and withdrawals for asingle hemostasis valve, the forces through each cycle are maintained atan acceptable level, at about 0.3 lbs on average, and within anadvantageously small variance in the range of measured force.

FIG. 5 shows the results of 96 insertion/withdrawal cycles of twodifferent catheters through a conventional hemostasis valve made ofunmodified silicone elastomers with external lubricating oil astypically used. The increasing forces after about teninsertion/withdrawal cycles is the result of lubricating oils beingremoved or wiped off the contacting surfaces. The changes in forces,from about 0.05 lbs to about 0.6 lbs, represent dramatically differentforces that would be required to insert and withdraw. Except for cycles4-10, the forces vary from nearly every cycle to the next.

DETAILED DESCRIPTION

Throughout this disclosure, applicants refer to texts, patent documents,and other sources of information. One skilled in the art can use theentire contents of any of the cited sources of information to make anduse aspects of this invention. Each and every cited source ofinformation is specifically incorporated herein by reference in itsentirety. Portions of these sources may be included in this document asallowed or required. However, the meaning of any term or phrasespecifically defined or explained in this disclosure shall not bemodified by the content of any of the sources.

The headings (such as “Introduction” and “Brief Summary”) used areintended only for general organization of topics within the disclosureof the invention and are not intended to limit the disclosure of theinvention or any aspect of it. In particular, subject matter disclosedin the “Introduction” includes aspects of technology within the scope ofthe invention and thus may not constitute background art. Subject matterdisclosed in the “Brief Summary” is not an exhaustive or completedisclosure of the entire scope of the invention or any particularembodiment.

As used herein, the words “preferred,” “preferentially,” and“preferably” refer to embodiments of the invention that afford certainbenefits, under certain circumstances. However, other embodiments mayalso be preferred, under the same or other circumstances. Furthermore,the recitation of one or more preferred embodiments does not imply thatother embodiments are not useful and is not intended to exclude otherembodiments from the scope of the invention and no disclaimer of otherembodiments should be inferred from the discussion of a preferredembodiment or a figure showing a preferred embodiment. In fact, thenature of the polymer compositions of the invention allow one of skillin the art to make and use the invention on any medical or surgicaldevice available or contemplated.

The phrases “self-lubricating polymer composition,” “self-lubricatingcomposition,” and “polymer composition of the invention” all refer to acomposition comprising a biocompatible polymer or blend of polymers anda biocompatible lubricant. In preferred embodiments, the composition iscomposed of polymer compounds that have not previously been usedtogether, or in a particular ratio or ratios, for use in a medical,surgical, or biomedical device.

The invention relates to the new, successful development of variousself-lubricating polymer compositions, and especially silicone elastomercompositions, which can be used to make a variety of medical andsurgical devices and thereby minimize friction forces during use whilemaintaining sufficient sealing characteristics. In one aspect,particular surfaces or elements of devices comprise a self-lubricatingpolymer of the invention. The medical devices of preferred interestinclude, but are not limited to, hemostasis valves of a variety of typesincluding those for cardiac catheters, medical tubing, sheaths andgaskets used in valves and insertion devices, ultrasound catheters, andsimilar devices.

In one general sense and without any intention to limit the scope to anyparticular explanation or mechanism for how it works, the inventionprovides a lubrication system for a polymer material, preferably asilicone elastomer material, through physical modifications of thepolymer matrix. Parts or components of a medical device can thus be madeto exhibit an improved surface lubricity and result in low frictionforces during use or in medical procedures, providing advantages by atleast improving the ease of use and/or comfort to a patient. Thus, it isone object of this invention to provide a self-lubrication mechanism fora surface or polymer matrix, such as a silicone elastomer matrix, suchthat any medical or surgical device made from the polymer matrix canrelease or spontaneously release embedded lubricant from the matrix oronto a contact surface(s) when the device is used. Accordingly, contactsurface lubricity and the resulting lowered frictional forces during usecan be reliably maintained throughout a procedure. Another object is toprovide a lubrication system for a silicone elastomer that isbiocompatible and can be used with a variety of medical and surgicaldevices and parts or elements thereof. Further, the lubrication andanti-friction performance characteristics are not degraded but canactually be enhanced by contact with blood, tissue, or medical fluids.

In preferred embodiments, the polymer compositions of the invention aredesigned to act like a matrix that allows the lubricant contained withinto continuously migrate to the surface of the part or device made of thepolymer. In effect, the lubricant is driven to the surface as thefriction forces of the insertion and withdrawal cycles move thelubricant or wipe the lubricant away. After manufacture, the surface ofthe polymer composition is essentially primed with lubricant. As thislubricant is used during insertion and withdrawal cycles, the lubricantin the matrix migrates to replace the surface lubricant. The result is aconstant friction force throughout the insertion and withdrawal cycles.Any of the polymer resins discussed here or in the Examples can form aneffective matrix for migration of lubricant. In addition, solid poroussilica powder or similar powders can optionally be added to increase theamount of lubricant contained in the matrix.

A number of polymers have been suggested as self-lubricating in avariety of applications, including: polyethylene; polyetherimide;polypropylene; polyetheretherketone (PEEK); polytetrafluoroethylene(PTFE) or Teflon (DuPont, Wilmington, Del.); Ultra High Molecular Weight(UHMW) polyethylene; polyoxymethylene or Delrin (DuPont, Wilmington,Del.); polyamide-imide (PAI) or TORLON (Solvay Advance Polymers,Alpharetta, Ga.); polyoxymethylene (POM), acetal resin, or Delrin(DuPont, Wilmington, Del.); and polyvinylidene fluoride or Kynar(Atochem Corporation). Some of these polymers do not possess thecombination of flexibility and lubricity desired for the medical andsurgical device applications noted herein. However, these polymers maybe modified with similar methods of the invention and used to producecatheters and sheaths, for example, having improved anti-frictionproperties. Furthermore, the preferred polymer compositions of thisinvention are biocompatible, such as biocompatible thermosettingsilicone elastomers and thermoplastic silicone elastomers.

In designing or selecting an acceptable or optimum polymer or blend ofpolymers for a particular device or part thereof, a method of theinvention can take into account the matrix-controlled lubricant releasemechanism. To optimize this mechanism or make it effective for aparticular use, one can modify raw polymer compositions. In one example,a silicone elastomer resin can be cured with either organic peroxidecrosslinking or, especially, by addition of a curing agent such assilicon hydride (SiH) and platinum as catalyst. In the latter approach,one can use liquid and/or solid lubricants, and preferably lubricantsthat are highly non-polar and chemically inert. The chemical inertcharacteristics can be important in avoiding combinations that interferewith a curing agent. The lubricants can also have low surface energiesthat are compatible with the polymer or blends used and, in the case ofthe silicone elastomers, can be about 20 mN/m (or dyne/cm). One or morelubricants with surface energies below 20 dyne/cm can be selected foruse, as explained below and in the Examples. Furthermore, the percentageof lubricant used and the amount available during the insertion andwithdrawal use can be changed to arrive at a desirable level for theanti-friction function for a particular part or medical device or methodcontemplated. One of skill in the art is familiar with varying theamount of lubricants and with additional compounds or additives, such asporous silica powders and the like, for increasing the amount oflubricant that can effectively create an anti-friction polymercomposition or material.

In one method of producing the polymer compositions of the invention,the one or more lubricants are incorporated into the raw polymer orblend, such as the raw, gum-like silicone elastomer resin, with atwo-roller mill compounding process as known in the art. Aftersufficient compounding to thoroughly mix the components, the lubricantsare well dispersed into the matrix or occupy molecular pores within thematrix. To make a medical device part or element, the compounded polymercomposition is molded, extruded or shaped and cured. In the case of asilicone elastomer, it is molded into shape and thermally cured. Thecuring process will create elastomeric, chemical crosslinks, whicheffectively trap the one or more lubricants in the polymer matrix. Onecan also consider the water repellency of non-polar lubricants and alubricant concentration gradient from the center to the surface of thepart. The limited chemical compatibility between the non-polar siliconeelastomer and the non-polar lubricants, for example, can synergisticallycontrol the release of the lubricants to the surface. One of skill inthe art is familiar with methods to produce concentration gradients.

Since silicone elastomers are one of the commonly used biomaterials inthe medical device industry, the examples here and the preferredembodiments include silicone elastomers. However, the invention is notlimited to the use of silicone elastomers or any particular polymer forthat matter.

Silicone elastomers possess high coefficients of friction and relativelylack lubricity characteristics, which leads to patient discomfort andpotential tissue trauma during medical procedures. The high frictionforces generated during the insertion and withdrawal of cathetersthrough an introducer containing a silicone elastomer, such as ahemostasis valve, have routinely challenged the medical devicesindustry. In practice, a hemostasis valve is externally lubricated withsilicone oil during manufacture. During use, silicone oil is quicklyremoved by the insertion and withdrawal actions and, therefore, thelubricating effect from the silicone oil is quickly lost. As a result,the frictional forces are extremely inconsistent during a medicalprocedure and begin to vary from the first insertion. At the beginningof a procedure, the friction forces are relatively low due to the effectof the externally added silicone oil, while in the midst of a procedurethe forces jump to an extremely high level as the oil dissipates, isremoved or rubbed off. This can influence the physician's use andcontrol of the device.

In the past, the industry has attempted to modify either hemostasisvalve design (such as in various design found in patent documents U.S.Pat. Nos. 6,776,774; 6,723,073; 6,702,255; 6,632,200; 5,807,350; and5,782,817) or the silicone elastomer materials by adding so-called solidlubricity enhancing additives, including bismuth oxychloride, PTFEpowder, titanium dioxide, graphite, (see for example U.S. Pat. No.5,562,632). Despite these attempts, none of hemostasis valves on themarket provide constant performance and low friction forces.

As a preferred example of the improvements possible under thisinvention, the performance of hemostasis valve as shown in U.S. Pat.Nos. 6,632,200 and 6,551,283 can be improved by incorporating theself-lubricating polymer composition at various parts. A siliconeelastomer is selected as well as liquid lubricants and/or solidlubricant additives. The liquid lubricants have low surface energiescompared to the silicone elastomer or blend selected and this betterensures the partial solubility and compatibility of the liquid lubricantinto the matrix of the silicone elastomer. By adjusting the lubricantused based upon the surface energy, an optimum release characteristicfrom the resulting cured polymer matrix and/or a controllable releaserate can be found. For example, incorporating a solid lubricant oradditional solid lubricant enhances the surface abrasive resistance,surface smoothness, and/or tear strength. Preferred liquid lubricantsare polyfluoropolyether synthetic oils and hydrocarbon-based syntheticoils, while preferred solid lubricants are low molecular weightpolytetrafluoroethylene powders, titanium dioxide, and baron nitrides.Both the liquid and solid lubricants are preferably chemically inert,devoid of chemical reactivity for the polymer or blend and curing agentused, and are preferably non-polar. This prevents them from interferingin the curing process. To increase the incorporation of a high orsufficient amount of synthetic oils or lubricants into the polymermatrix, a porous filler, such as porous silica, can optionally be added.

Generally, the self-lubricating polymer compositions of siliconeelastomers contain 0.1 to 20 phr (part Per Hundredth Resin by weight)liquid lubricants and/or 0 to 20 phr solid lubricants. However, variouspreferred ranges of liquid and/or solid lubricant concentrations can beselected for use, including 1-20 phr, 1-5 phr, 3-5 phr, 3-6 phr, 4-6phr, 3-10 phr, 1-10 phr, 1-15 phr, 5-15 phr, 8-10 phr, 10-20 phr, 15-20,and 5-10 phr, for example, can be used for either or both of the solidand liquid lubricant, alone or in combination. By selecting a fluid-likelubricant that has similar surface energy to that of the cured siliconeelastomer but is chemically-inert, one of skill in the art can be betterassured that the lubricant can be effectively contained in the molecularpores of the cured matrix due to surface tension. At the same time, thelubricants do not interfere with the chemical reaction of curing.Therefore, after curing, the fluid-like lubricant can be released underfriction forces, preferably with continuous migration driven by theconcentration gradient existing from the bulk material to the surface.

The following are some examples of the preferred self-lubricatingpolymers of silicone elastomers of the invention in whichpolyfluoropolyether (PFPE) or perfluoroalkylether synthetic oil (havingsurface energies of 18 to 20 mN/m or dyne/cm) are used as liquidlubricants. In addition or alternatively, boron nitride or low molecularweight polytetrafluoroethylene (PTFE) micropowders may be used as solidlubricants to adjust anti-friction or abrasion resistance and/or tearstrength.

A preferred example of a medical device or part thereof to demonstratethe improved anti-friction characteristics of the polymer compositionsof the invention is a hemostasis valve. The valve may be reliably usedwith a wide variety of diameters for an inserting device, up to about 9F (3 mm) catheters and down to guidewires of about 0.014 in. (0.35 mm).A hollow tube can also be used, as in a molded 8 F introducer that canalso be used as a catheter for various purposes.

Illustrative Examples

Together with a mixture comprised of the appropriate tubing or gasketbody materials, a combination of the silicone elastomer and lubricant,such as PFPE, is placed in a previously-heated mold and is then heatedto a temperature of about 130 to 200 degrees C., preferably at a moldingclamping pressure of about 0.5 to 25 MPa, and preferably for aprocessing time of about 1 to 20 minutes, to obtain the finishedproduct. The silicone rubber or elastomer selected may be one with aparticular Durometer hardness (for example, the “Shore A scale” which,for the purposes of this invention, includes similar or any comparablehardness scale for polymer compositions as known in the art). Forexample, anywhere between about 10 durometer to about 90 durometer canbe used. The combined elastomer/lubricant polymers can then be evaluatedon certain valve body designs having differing diameters. Insertionforce measurements and leakage can then be conducted. An optimal polymercombination can be thus selected for any particular combination ofmedical device parts or elements, such as a catheter and hemostasisvalve, valves or gaskets and various introducers, such as steerableintroducers or Swartze introducers, and similar parts of functionalparts of medical and biological devices. Usually, the insertion force isdesired to be low and no leakage present.

The components of the polymer composition can also be varied to optimizehardness, weight, and thickness, and one skilled in the art is familiarwith selecting silicone elastomers, for example, that can result in afinal product having a desirable or optimal ranges for any or all ofthese characteristics. In one embodiment, any of the Elastosil orSilastic series of liquid silicone rubber can be selected. Themethylvinyl silicone resin Silastic Q7-4735 is used in the examplesbelow, but many other resins can be selected and similarly used, asnoted above, including Silastic Q7-4720.

Example 1

A silicone elastomer resin based upon methylvinyl silicone (SilasticQ7-4735) is selected as the polymer matrix. A liquid lubricant, PFPEsynthetic oil, is used at 5 parts per hundred of rubber (phr). Thecomponents are mixed using a two-roller mill. The resulting compound istransfer-molded into the gaskets of a hemostasis valve, as noted above,and then post-cured at 150 degrees C. for 2 hours.

Example 2

The same polymer resin as Example 1, but a liquid lubricant (PFPEsynthetic oil) is used at 10 phr.

Example 3

The same polymer resin as Example 1, but a solid lubricant (lowmolecular weight PTFE micropowder) is used at 3 phr, and a liquidlubricant (PFPE synthetic oil) is used at 5 phr.

Example 4

The same polymer resin as Example 1, but a solid lubricant (lowmolecular weight PTFE micropowder) is used at 8 phr, and a liquidlubricant (polyfluoroalkylether synthetic oil) is used at 8 phr.

Example 5

The same polymer resin as Example 1, but a solid lubricant (boronnitride micropowder) is used at 5 phr, and a liquid lubricant(polyfluoroalkylether synthetic oil) is used at 10 phr.

Example 6

A thermoplastic silicone elastomer, Geniomer 200, is selected as theresin, a solid lubricant (low molecular weight PTFE micropowder) is usedat 3 phr, and a liquid lubricant (polyfluoroalkyl ether synthetic oil)is used at 8 phr. The ingredients are mixed into a self-lubricatingpolymer composition using a solvent or melt compound approach, as knownin the art. The resulting composition is then injection molded into ahemostasis gasket as noted above.

Example 7

The utility of the self-lubricating polymer compositions and the partsor elements made from them can be tested under cyclic insertionconditions at constant forces. Unlike currently available products, theinsertion forces are very stable at about 0.25 lbs during one hundredinsertion cycles, even when five different 6F catheters are used. Incomparison, the insertion forces vary from 0.1 to 0.6 lbs during theparallel tests using currently available materials.

As shown in FIG. 4, the repeated insertion and withdrawal cycles of theself-lubricating polymer of Example 1 show very little changes in forcesmeasured over the 14 cycles. Even when new catheters are used on thesame hemostasis gasket, the forces remain constant. Thus, theself-lubricating polymers of the invention allow a greatly improvedconsistency in the insertion and withdrawal processes. Comparing to theFIG. 5 results of a conventional polymer and hemostasis gasket, theforces vary over the entire period of the experiment and there is adramatic and fairly constant increase in required forces at about cycle10, presumably when the externally applied lubricant is no longereffective.

The reduction in friction forces can be demonstrated in a method that isillustrated in FIG. 1, in which a catheter is inserted into the bloodvessel through an introducer that has a hemostasis value contained inits hub. The lubricant releasing from the self-lubricating polymercomposition of the hemostasis valve effectively self-lubricates thecontact surfaces between the catheter and hemostasis valve, leading tothe reduction in the friction forces and/or substantially constant andpredictable friction forces.

Although various embodiments of this invention have been described abovewith a certain degree of particularity, or with reference to one or moreindividual embodiments, those skilled in the art could make numerousalterations to the disclosed embodiments without departing from thespirit or scope of this invention. It is intended that all mattercontained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative only of particularembodiments and not limiting. All directional references (e.g.,proximal, distal, upper, lower, upward, downward, left, right, lateral,front, back, top, bottom, above, below, vertical, horizontal, clockwise,and counterclockwise) are only used for identification purposes to aidthe reader's understanding of the present invention, and do not createlimitations, particularly as to the position, orientation, or use of theinvention. Connection references (e.g., attached, coupled, connected,and joined) are to be construed broadly and may include intermediatemembers between a collection of elements and relative movement betweenelements unless otherwise indicated. As such, connection references donot necessarily infer that two elements are directly connected and infixed relation to each other. It is intended that all matter containedin the above description or shown in the accompanying drawings shall beinterpreted as illustrative only and not limiting. Changes in detail orstructure may be made without departing from the basic elements of theinvention as defined in the following claims. The invention is notlimited to any particular embodiment or example given here. Instead, oneof skill in the art can use the information and concepts described todevise many other embodiments beyond those given specifically here.

1. A biocompatible, self-lubricating polymer composition consisting essentially of: a polymer matrix of dimethyl and methylvinyl siloxane copolymers, wherein the polymer matrix is selected from the group consisting of: (a) a polymer matrix, measured as in-mold cured for 10 minutes at 116° C., that has a specific gravity of 1.11, a durometer of 22 in Shore A hardness scale, and a tensile strength of 1347 psi and (b) a polymer matrix, measured as in-mold cured for 10 minutes at 116° C., that has a specific gravity of 1.12, a durometer of 35 in Shore A hardness scale, and a tensile strength of 1427 psi, and a polyfluoropolyether (PFPE) synthetic oil at a concentration of about 1 to about 20 parts per hundred by weight (phr), wherein the PFPE synthetic oil migrates through the polymer matrix during the use of the biocompatible, self-lubricating polymer composition, and wherein the migration of PFPE synthetic oil maintains consistent surface lubricity when exposed to frictional force.
 2. (canceled)
 3. The self-lubricating polymer composition of claim 1, wherein the PFPE synthetic oil is present at about 4 to about 20 phr.
 4. (canceled)
 5. The self-lubricating polymer composition of claim 1, wherein the PFPE synthetic oil is present at about 4 to about 6 phr.
 6. (canceled)
 7. The self-lubricating polymer composition of claim 1, further comprising a biocompatible, solid lubricant micropowder. 8-28. (canceled)
 29. A method of producing a biocompatible self-lubricating polymer for use in a medical device, comprising: mixing a polymer matrix of dimethyl and methylvinyl siloxane copolymers having a durometer hardness of about 10 to about 90 on the Shore A scale with at least one liquid lubricant having a surface energy of about 10 to about 20 dyne/cm with a two-roller mill compounding process until the lubricant occupies the molecular pores of the matrix; molding the mixture into the desired shape; and thermally curing the molded shape until the lubricant is trapped in the polymer matrix.
 30. The method of claim 29, wherein the liquid lubricant is PFPE synthetic oil and PFPE is present at about 4 to about 10 phr.
 31. The method of claim 29, wherein the liquid lubricant is PFPE synthetic oil and PFPE is present at about 4 to about 6 phr.
 32. The method of claim 29, wherein the polymer matrix has a durometer hardness of about 30 to about 40 on the Shore A scale.
 33. The method of claim 29, wherein the medical device is a tube having an outside diameter from about 5 mm to about 2 mm and an inside diameter of about 3.5 mm to about 1.5 mm.
 34. The method of claim 29, wherein the medical device is an introducer.
 35. The method of claim 29, wherein the medical device is a hemostasis valve.
 36. The method of claim 29, further comprising adding a biocompatible, solid lubricant micropowder to the mixture. 37-40. (canceled)
 41. The method of claim 29, wherein the biocompatible self-lubricating polymer is used in the production of a sheath, tube or tubing, whereby the tube, sheath or tubing comprises at least about 10% or more of the self-lubricating polymer over its insertion length or receiving length. 42-56. (canceled) 